This invention relates to an apparatus for controlling the timing, and particularly the ignition timing, of an internal combustion engine. More particularly, it relates to an engine timing control apparatus which is less susceptible to engine noise than conventional timing control apparatuses.
An engine timing control apparatus typically includes a signal generator for generating an output signal indicating a prescribed reference position of the crankshaft of an engine. The ignition timing, the fuel injection timing, and the time at which the ignition coil is made to begin conducting are measured from this reference position, so it is very important to detect the reference position accurately. A common type of signal generator for engine control is a crankshaft position sensor which generates a pulse train having gaps of a prescribed length therein at regular intervals. The gaps in the pulse train identify the occurrence of the reference position.
At the time of ignition in an engine, much electrical noise is generated. In a conventional engine timing control apparatus, the gaps in the pulse train generated by the signal generator coincide in time with ignition, and the electrical noise produced by ignition can make it difficult to identify the gaps. Therefore, the reference positions corresponding to the gaps can not be detected, and the engine timing can not be accurately controlled.